In a UMTS (Universal Mobile Telecommunications System) network, attempts are made to optimize features of the system, which are based on W-CDMA (Wideband Code Division Multiple Access), by adopting HSDPA (High Speed Downlink Packet Access) and HSUPA (High Speed Uplink Packet Access), for the purposes of improving spectral efficiency and improving the data rates. With this UMTS network, long-term evolution (LTE) is under study for the purposes of further increasing high-speed data rates, providing low delay, and so on (non-patent literature 1).
In a third-generation system, a transmission rate of maximum approximately 2 Mbps can be achieved on the downlink by using a fixed band of approximately 5 MHz. Meanwhile, in an LTE system, it is possible to achieve a transmission rate of about maximum 300 Mbps on the downlink and about 75 Mbps on the uplink, by using a variable band which ranges from 1.4 MHz to 20 MHz. Furthermore, with the UMTS network, a successor system of an LTE system is also under study for the purpose of achieving further broadbandization and higher speed (for example, “LTE-advanced” (LTE-A)).
In the LTE-A system, carrier aggregation (CA) to achieve broadbandization by aggregating a plurality of fundamental frequency blocks (CCs: Component Carriers) of different frequency bands is under study. Also, with the LTE-A system, an agreement to make a single fundamental frequency block a frequency band (for example, 20 MHz) that can be used in the LTE system has been made in order to achieve broadbandization while maintaining backward compatibility with the LTE system. For example, when five fundamental frequency blocks are aggregated, the system band becomes 100 MHz.